Could you use 5.45x39 bolt to shoot 5.56 ammo?

Okie to clear things up.... I would like to know if I buy cope's 5.56 bulgy barrel, could I use 5.45 bolt and bolt carrier and shoot .223 out of a 5.56 barrel or I have to get a 5.56 bolt and carrier? Sorry if this is like 100th time you've read about this question, but I tried to search and found nothing.

also many 5.45 bolts dont have spring loaded firing pins, I would highly advise having a spring loaded firing pin on a 223 so you can safely shoot commercial ammo with the softer primer. especialy inlight of the atf recently prosicuting when guns that accidently double. not to mention the saftey factor.

Im not sure if any 5.45 bolts do have the spring loaded pin. Im not an expert there. my tantal dosent it also small stem.

if you use a 7.62x39 carrer you will need to narrow it were it runs through the mag as well.

The Bulgarian 5.56 bolt is large stem but the bolt carrier is cut to clear the narrower opening in the 5.56 magazine. The Bulgarian 5.56 barrels are designed for a small lug bolt. Using a 5.45 Bulgarian bolt will force the barrel farther forward in the trunnion that designed. This moves the rear sight block farther back and then the gas tube and then the gas block. The gas port is already in the Bulgarian barrel. The other option is a Romanian 5.45 bolt with the small lugs. The 223 Saiga bolt has large lugs similar to the Bulgarian 5.45 bolt.

I use 222 Remington (not 223) brass to handload 5.45 so the 5.45 bolt face will work with 223 cases but it is looser than the Bolgarian 5.56 bolt face and the 223 Saiga bolt face. The 223 Saiga ejector is about .010" longer than the 5.45 Romanian ejector. tHis shouldn't make much difference. The 7.62x39 Saiga ejector is .010" longer than 7.62 Romanian ejector. K-var used to sell the same Romanian rails as "5.45/5.56" and they semm to work alright.